This patent document relates to wireless communications.
Wireless communication systems can include a network of one or more access points (AP) to communicate with one or more wireless stations (STA). An AP can emit radio signals that carry management information, control information or users' data to one or more wireless stations, and a station can also transmit radio signals to the access point in the same frequency channel via time division duplexing (TDD) or in a different frequency channel via frequency division duplexing (FDD).
IEEE 802.11 is an asynchronous time division duplexing technology for operation of a wireless local area network (WLAN). The basic unit of WLAN is a basic service set (BSS). An infrastructure BSS is the BSS with stations that communicate through associating with an Access Point (AP) to connect to the wired network or Internet. In a BSS, both access point and stations share the same frequency channel via using Carrier Sensing Multiple Access with Collision Avoidance (CSMA/CA) technology, a kind of TDD mechanism, for multiple access and data transmission.